Ensuring that all pilots receive adequate rest is key to maintaining a safe aviation system, according to a press release issued by the Federal Aviation Administration. While current FAA rules are fundamentally sound and have contributed to an excellent safety record, fatigue remains a very real aviation safety issue, according to the FAA. The FAA is interested in any new fatigue research that would assist the agency with enhancing its rules and that promotes industry best practices for fatigue risk management.

Airplanes operate globally in 24 time zones. Domestic short leg, multi-leg, and long-haul flights all present challenges. Engine technology has evolved enabling airplanes to fly much further than in the past. Since many air carriers fly non-stop ultra-long-range flights, the FAA continues to evaluate the latest research on the effects of time zone changes on circadian rhythm and time zone changes to mitigate pilot fatigue. The FAA continues to raise awareness of fatigue and mitigation techniques, according to the press release.

The FAA last proposed updating the rules in 1995 but, based on industry comments, the rule was not adopted. Since then, the agency has reiterated the rules and kept pace with a changing industry by allowing airlines to use the latest fatigue mitigation techniques to enhance safety.

Regulations limiting flight time and pilot rest have been in place since the 1940s. The rules for domestic flights do no explicitly address the amount of time a pilot can be on duty. Rather, the rules address flight time limitations and required rest periods. Current FAA regulations for domestic flights generally limit pilots to eight hours of flight time during a 24-hour period. This limit may be extended provided the pilot receives additional rest at the end of the flight.

However, a pilot is not allowed to accept, nor is an airline allowed to assign, a flight if the pilot has not has at least eight continuous hours of rest during the 24-hour period. In other words, the pilot needs to be able to look back in any preceding 24-hour period and find that he/she has had an opportunity for at least eight hours of rest. If a pilot’s actual rest is less than nine hours in the 24-hour period, the next rest period must be lengthened to provide for the appropriate compensatory rest. Airline rules may be stricter than the FAA’s regulations if the issue is part of a collective bargaining agreement.

Flight time and rest rules for U.S. air carrier international flights are different from the rules for domestic flights. International flights can involve more than the standard two-pilot crew and are more complex due to the scope of the operations. For international flights that require more than 12 hours of flight time, air carriers must establish rest periods and provide adequate sleeping facilities on the airplane for in-flight rest.

An air carrier may not schedule any pilot and no pilot may accept an assignment for flight time in scheduled air transportation or other commercial flying if that pilot’s total flight time will exceed the regulatory limits.

It is the responsibility of both the air carrier and the pilot to prevent fatigue, not only by following the regulations, but also by acting responsibly while serving the traveling public, according to the FAA. This means taking into consideration weather conditions, air traffic, the health of each pilot, and any other personal circumstances that may affect a pilot’s performance. The FAA has recommended that air carriers include fatigue training as part of their crew resource management training programs.

In 1995, the FAA proposed a rule to change flight time and rest limits. The agency received more than 2,000 comments from the aviation community and the public. Most of those comments did not favor the rule as proposed, and there was no clear consensus on what the final rule should say. Highlights of the 1995 proposal:

Reduce the number of duty hours (the time a flight crewmember is on the job, available to fly) from the current 16 hours to 14 hours for two-pilot crews. It would have allowed up to 10 flight hours in the 14 duty hours. Current rules allow up to 16 hours continuous duty time.

Additional duty hours would be permitted only for unexpected operational problems, such as flight delays. In no event could such delays add more than two hours to the pilot’s duty day.

Airlines could no longer schedule pilots in advance in a manner that exceed the duty time.

To ensure that pilots have an adequate opportunity to rest, off-duty time would be increased from eight hours to 10 hours under the proposal.

Pilots would have to be given at least one 36-hour off-duty period every seven days. Current rules call for a 24-hour period.